A replacement to the Alaskan Way Viaduct is inevitable, thus I would vote in favor of a tunnel. First and fore most, our state is in dire need of jobs and this project would provide tens of thousands of jobs throughout the next nine years.
Next, Seattle is well-known for traffic problems. Nothing will better relieve conjestion than additional roadways. Seattleites that currently use public transportation are unlikely to revert back to the roads just because a new tunnel is in existance. Yes, the tunnel could free up some traffic, but it is not likely to solve the problem all together.
Finally, the current viaduct is dangerous. Numerous experiements have proven that it is likely to collapse in an earthquake. A safe and effective alternative is necessary.